1. Field of the Invention
The present invention relates to an air-conditioning system. More particularly, the present invention relates to a mixing chamber used in an air-conditioning system for mixing cool air with warm air.
2. Description of the Prior Art
The U.S. Pat. No. 4,517,813 discloses a mixing device suitable for use in an air-conditioning apparatus for a large carrier aircraft. The mixing device is specifically designed to mix cool air from an air-conditioning unit with warm air which has been drawn from passenger compartments to thereby produce conditioned air. As shown in FIGS. 4 and 5, the mixing device shown in the U.S. patent includes a cylindrical mixing chamber 1 which is provided at a lower end portion with a plurality of air inlet ports 2. Cool air is transported from an air-conditioning unit through meets at a duct 6 with warm circulating air which has been drawn from the passenger compartments and transmitted through a filter 4 provided in a duct 5. The mixture of the cool air and the warm air is then introduced tangentially into the mixing chamber 1.
The air introduced into the mixing chamber 1 is then form an upwardly directed swirling flow and the cool air is mixed with the warm air during the course of upward flow in the mixing chamber 1. The mixed air is then discharged through discharge ports 7 to be distributed to desired portions in the aircraft. The cool air is passed through a water separator before it is introduced into the duct 3. However, it is impossible to remove moisture completely so that the mixing device is provided with a further water separator for preventing water from being carried to the passenger compartments. For the purpose, there is an angle member which is attached to the inner wall surface of the mixing chamber to form a spirally extending water discharge passage 8 which is arranged to cross the spiral upward air flow in the mixing chamber 1. The water content in the air is deposited under the influence of the centrifugal force on the inner wall surface of the mixing chamber 1 and directed to the discharge port 9 which is formed in the lower part of the mixing chamber 1. A water capturing ring 24 is provided right above the water discharge passage 8 for capturing water which has not been collected by the passage 8. The water captured by the ring 24 is directed to the passage 8 to be discharged through the discharge port 9.
It has been found that the mixing device as shown by the U.S. patent has a problem that a substantial part of the water which has been deposited on the inner wall surface of the cylindrical mixing chamber 1 and introduced into the discharge passage 8 to be discharged is apt to be caught again by the upward air stream to be accompanied thereby to the passenger compartments. This phenomenon is particularly significant when the air introduced into the mixing chamber has a high moisture content and/or the spiral upward air flow is of a high flow speed. The U.S. patent shows a structure wherein the mixing chamber 1 is provided at the exit end portion with a flow straightening grid, however, the grid is not sufficient to capture the water content to a satisfactory extent.